Chewing
Problems associated with the teeth can have a negative impact on digestion as food may either be lost or enter the stomach whole. Chewing produces saliva that contains bicarbonate which helps neutralise acid in the stomach and eases the passage of food into the stomach.

Stomach
The collection point for food. Top part is a more neutral environment (around pH7) and contains some fermenting bacteria so a little digestion takes place here. The wall of the upper part is prone to ulceration from excess acid e.g. where horses are stressed or on high cereal diets. The lower part of the stomach has acid producing glands in the gut wall creating a more acidic (low pH) environment which helps to kill off harmful bacteria that enter along with the food.

Small Intestine
Where enzymes are released which breakdown starch e.g. from cereal feeds, more available types of protein and some minerals, which are absorbed through the gut wall. pH levels creep back to neutral during this phase.

Caecum
Equivalent to the human appendix. This structure contains a diverse population of microbes that ferment material (mainly fibre) that the horse cannot digest with its own enzymes in the small intestine. These microbes break down forage at a neutral pH and produce nutrients in a form that the horse can absorb and use itself.

Fibre
The horse is designed to eat and process fibre. It encourages chewing (good for saliva production), decreases dry matter of food in the stomach to prevent excessive acid production (reducing the risk of ulcers), maintains healthy hind gut function and draws water into the hind gut (for hydration).

Fore gut
Stomach and small intestine. Food processed over a period of one to two hours although some speeds through in half an hour.

Hind gut
Caecum and large intestine. Digestive process takes an average of two to three days.

Microflora/microbial population
The mix of bacteria or 'bugs' that live in the gut. Different bacteria inhabit fore and hind gut.

Prebiotics
Two principal types commonly used are: 1. Mannanoligosaccharides (MOS) that bind potentially harmful bacteria in the gut and allow beneficial bugs to dominate; also assists immune function. 2. Fructanoligosaccharides (FOS) that deliver fructans into the fore gut to 'feed' the acid producing bacteria.

Probiotics
Meaning 'for life' (as opposed to antibiotic). Yeast cultures have a probiotic mode of action but the term is generally accepted as meaning products that supplement lactic acid bacteria to the diet. Probiotics top up the beneficial bacteria to improve conditions within the foregut. They require EU registration for use in animal feeds but no trial data is currently available on equines.

Yeast culture
A particular strain of yeast (e.g. strain 1026 as in Yea-Sacc® 1026) selected for its beneficial effect on hind gut fermentation. It helps maintain neutral pH in the hind gut and stimulates the friendly bacteria for optimum gut function. Yeast cultures are grown on a medium and then dried for inclusion in feed.

Chelated minerals
Minerals that have been 'bonded' to short-chain proteins (amino acids) to improve absorption from the gut. Chelates mimic the way minerals occur naturally in the diet and are absorbed using different biochemical pathways. Also known as organic proteinates or bioplex minerals.

Sel-Plex
A high selenium yeast providing selenium as nature intended i.e. bound in methionine and other amino acids for easy absorption. A natural alternative to the chemical 'sodium selenite' commonly used in animal feed (developed as a petrochemical sterilising agent).

Anti-oxidants
Life is a battle against oxidation (going rancid). As a preservative, antioxidants are used to extend shelf life of feed, stopping oils and fats from going rancid and protecting vitamins from pro-oxidant action of minerals which can destroy them over time. In the body, antioxidant vitamins (A, C, E) and minerals (selenium, zinc and copper) mop up toxins (free-radicals/oxidising agents) that can cause cell damage from the brain through to the immune system and cartilage.

Electrolytes
Essential body salts that are lost in sweat. Failure to replace electrolytes can affect certain body functions associated with muscle and performance.